Study On Calculation Method Of Performance And Leakage Characteristics Of Carbon Fiber Brush Seal

As a kind of flexible high-speed dynamic sealing device,brush seal has a good application prospect in dynamic sealing parts of major equipment,such as gas path of aircraft engines,rocket motors and gas turbines.However,its theoretical research and practical engineering application are limited due to the problems of friction heat burning tip,wear,and difficult calculation of leakage in high speed engineering application.Therefore,in this paper,carbon fiber is instead of high temperature alloy metal brush,the structure of brush seal is designed.It is hoped that when it is applied to high-speed and high-temperature occasions,not only ensure the flexibility and good sealing performance of brush seal but also avoid the defects such as burning tip and hair breakage of traditional metal brush seal.For this reason,the numerical calculation method of brush seal was firstly studied,and the leakage performance calculation model of brush seal was established based on the flow theory of porous media.The paper adopts the method of treating the brush beam area into porous medium,establishes the control equation based on the Navier-stoke equation,and determines the calculation method of brush seal porosity,equivalent diameter and brush wire resistance to fluid.Thus the model of brush seal leakage flow is constructed.Based on the Fluent software,the leakage flow characteristics of two brush seals under the limit thickness are simulated.The results show that the actual leakage is within the leakage limit of the two types of brush thickness calculated by the model simulation.In order to better analyze the performance of brush seal,the thickness and porosity of brush beam are modified in combination with experimental data.The results show that the theoretical calculation results are in good agreement with the experimental results,which verifies the feasibility of the brush seal leakage flow model.Then,the carbon fiber brush seal is numerically calculated by using the modified model.under the same conditions of calculation domain,grid division and boundary conditions as metal brush seal.The velocity,pressure and leakage characteristics of fluid flowing through carbon fiber brush seal and metal brush seal under different pressure difference and rotating speed are studied,and the performance results of two brush seal are compared and analyzed.The results show that under the same working condition,the leakage of carbon fiber brush seal is smaller than that of metal brush seal,and the leakage performance of carbon fiber brush seal is less sensitive to the pressure difference between upstream and downstream and has better sealing performance.Finally,the effects of structural parameters on the leakage characteristics of carbon fiber brush seal are studied.The results show that the leakage of carbon fiber brush seal increases linearly with the increase of inner diameter and height of rear baffle.The height of the front baffle has little effect on the leakage,and the influence of brush wire length and arrangement angle on the leakage of brush seal is nonlinear.It is necessary to further explore and study its influence law.The research provides important reference for high performance brush seal design and engineering application.